Filtering Large Lenses

[sperdynamite]

Here I thought I was future proofed with my tidy collection of 100mm ND Grads and colored plates from Lee and Formatt HiTech... Alas no, for my new-to-me Caltar 360mm is a dastardly 112mm thread.

Would it be absurd to hold a 100mm colored filter in front of the lens during exposure? Or do people attach rear mounted Lee adapters? It would be something of a tight fit... But with threaded filters well into the triple digits here I just thought I'd ask for some solutions.

[Dan Fromm]

Look on ebay for 150 x 150mm Wratten gels.

[Corran]

What format are you shooting it on?

If it were me, I'd buy an appropriately-sized step-down ring and use your 100mm filters with the largest adapter they make. You'll cut off a lot of image circle, but depending on the format, that may not matter. If you need the image circle, then perhaps the next step would be to check if the rear cell has threads for normal filters, or use a slip-on gel filter adapter there with smaller gels (focus with the gel in place).

Gels in front of the lens would personally be my last resort due to issues with flare and such in the field, but perhaps that's an option for you as well as Dan points out.

[tgtaylor]

A professional option would be the Cokin X-Pro holder with the 112mm adapter ring which screws into the threads on the lens. There are 3 versions of this holder available: this link is for the more expensive version: https://www.bhphotovideo.com/c/product/1419112-REG/cokin_cbxe01_x_pro_evo_filter_holder.html

Thomas

[Eric Woodbury]

Six inch gels or gels cut from lighting gels. Or use gels taped behind the lens. If you aren't shooting wide open, then a smaller filter on the front shouldn't inhibit the image circle.

[Doremus Scudder]

It's just fine to hand-hold a filter in front of the lens as long as you don't introduce vibration, etc. I've done it many times, with both glass and gel filters. However, you need to be sure your filter covers the entire lens completely. If the front element on your lens is significantly smaller than the 112mm filter size, you might get away with it. FWIW, I've taped filters to the lens barrel many times with good results. I use medical "skin tape" because it sticks well but comes off easily without leaving a residue.

Any filter that goes between lens and film has to be of superb optical quality and focusing must be done with the filter in place because of the focus shift. Behind-the-lens filters are a viable option too. The problem in the field is that you have to remove either the lens or the camera back to mount the filter. If the lens has threads in the rear element and you have an adapter permanently attached, this isn't so fiddly, but if you have to juggle adapter, lens and filter, or hold your camera back between your knees while dealing with filter mounting inside the bellows, things can be a hassle.

12 mm is 1.2 cm is .47 inches and is quite a bit of difference from 100mm. I wouldn't step down to the 100mm size unless I really knew I didn't need the image circle. And, I'd really check for vignetting every time I did (if I did).

The best solution is to get a 112mm solution for the front... glass filters are likely pretty expensive. Stepping up to larger Cokin filters or gels would be an option that would work with your other lenses too, albeit a bit larger and more cumbersome.

Maybe just getting the one or two filters you use most in gel (and an appropriate mounting solution) or glass would be a good starting point. I know that most of my work is done with no filter and the most used filters are PL and #15 followed by #11; I could get by with those two or three pretty well.

Best,

Doremus

[Tin Can]

My biggest filter is B+W 122mm Yellow MRC 022M Filter which B&H used to stock